he purpose of this Wound Care Guide is to create a RESOURCE that fosters a more wholistic approach to the management of pressure injuries by simultaneously treating supine and seating postures. Our goal is to give a better understanding of the critical role appropriate wheelchair configurations and equipment choices play in the prevention and treatment of pressure injuries. After reading this guide, you as a Health Care Provider will be able to:

1

Identify the role wheelchair support surfaces play in the prevention and healing of a pressure injury

2

Ensure simultaneous consideration of BOTH supine and seated postures in the prevention and treatment of pressure injuries by addressing pressure, shear, and microclimate

3

Define each team member's role in prescribing and obtaining the appropriate wheelchair models, skin protection cushions, back supports, and accessories to minimize the risk of and assist in the healing of existing pressure injuries

BeyondThe Bed

Before we dive into the management of pressure injuries, let's go over the some terminology and definitions for pressure injuries according to the National Pressure Ulcer Advisory Panel.

What is a pressure injury?

According to the NPUAP: "A pressure injury is localized damage to the skin and/or underlying soft tissue usually over a bony prominence or related to a medical or other device. The injury occurs as a result of intense and/or prolonged pressure or pressure in combination with shear. The tolerance of soft tissue for pressure and shear may also be affected by microclimate, nutrition, perfusion, comorbidities and condition of the soft tissue." (19)

In April of 2016, the National Pressure Ulcer Advisory Panel, or NPUAP, changed what we once knew as decubitus ulcer or pressure ulcer to pressure injury to have uniform terminology throughout the wound care world.

What are the new definitions for the pressure injury staging?

Stages of Pressure Injuries:

Stage 1

Intact skin with a localized area of non-blanchable superficial reddening of the skin. Presence of blanchable redness or changes in sensation, temperature, or firmness may precede visual changes.

Stage 2

Partial-thickness skin loss or blister. The wound bed is viable, pink or red, moist. These injuries commonly result from adverse microclimate and shear in the skin over the pelvis and shear in the heel.

Stage 3

Full thickness skin loss, in which adipose (fat) is visible in the ulcer and granulation tissue and rolled wound edges are often present. Slough and/or eschar may be visible. Undermining and tunneling may occur.

Beyond the Bed

What are the top areas of common pressure injury development in supine?

Heel

Toe

Sacrum

Coccyx

Ischial Tuberosity

Occiput

Scapula

Spinous Process of Vertebrae

Elbow

What are we missing in the treatment of a pressure injury?

As health care providers—especially physicians, nurses, and specialized therapists in wound care—we understand bedside treatment well. We search for the most appropriate support surfaces and stay up-to-date with the most innovative technologies to promote healing and prevention of new pressure injuries.

However, too often we forgot a critical piece of the puzzle in the fight against pressure injuries: prevention and treatment at the wheelchair level!

The above words and concepts jump to mind when discussing pressure injuries and they are just as critical to understand from the seated posture as they are in supine.

Are the common areas of pressure injury different in supine vs the seated posture?

Most patients that develop a pressure injury spend the majority of their time in bed or in a wheelchair, placing the skin and tissue under the bony prominences at risk. These "at risk" areas are almost identical bedside and in the wheelchair making it imperative to simultaneously prevent and treat pressure injuries from the supine and seated posture.

Why are these common areas at such high risk to develop a pressure injury?

In the wound care world, we are in a constant battle against the extrinsic factors of pressure injury development.

The extrinsic factors and the threat they pose to the patient in relation to the bed is well understood, BUT...

Do we consider these factors in relation to the wheelchair?

WE SHOULD!

Why do the extrinsic factors pose such a threat to a patient in the seated posture?

While seated, our weight goes directly through the pelvis and spine, leaving the bony prominences very susceptible to pressure, shear, and microclimate. This is the nature of a seated posture. With the constant compression of the skin and tissues:

a pressure injury can develop in four to six hours after sustained loading and at times in as little as an hour

and by allowing our patients to sit all day with low-quality cushions and back supports, we run the risk of "un-doing" the advancements we made with bedside treatments

What should our goal be when treating a pressure injury?

Treatment at both surfaces need simultaneous attention to minimize the risk of development or assist in the healing of an existing pressure injury. Provide the best equipment possible for all support surfaces!

What is my role in the equipment ordering process?

No matter if you are the doctor, nurse, therapist, or ATP, you play a critical role in the recognition, treatment, and prevention of a pressure injury. Take a look at the following flow chart to understand your role and how it fits in the big picture of providing every patient with the appropriate equipment.

Skin Changes that Increase Susceptibility

Understanding the Population

Why is a wheelchair user's skin more susceptible to a pressure injury?

Most wheelchair users are dealing with factors that compromise skin integrity due to:○ multiple co-morbidities○ disease processes known to directly affect skin integrity such as IDDM, vascular insufficiencies, etc○ the natural progression of aging

What layers of skin become compromised with disease and/or aging?

Since changes occur at each layer of the skin through disease processes and/or natural aging, ALL the layers are compromised and make a patient more susceptible to a pressure injury.

Skin Changes at Each Layer

Let's compare young/healthy skin to aged/diseased skin and see why our patient population is at higher risk for pressure injury.

Why does thinner skin increase the risk of developing a pressure injury?

Overall skin thickness decreases by 6.4% per decade, increasing:

○ the risk of skin tears with minimal pressure, trauma, and shear forces

○ the susceptibility of the deeper layers of skin to the extrinsic factors as the epidermal layer is broken open more easily

○ the amount of time needed to heal a pressure injury

Layers of skin changed: Epidermis, Dermis, Hypodermis

How does having a reduction in sebaceous glands and sweat glands increase the risk of developing a pressure injury?

Fewer Sebaceous Glands

Less sebum (oil) production removes the oily coating from the superficial layer of skin, therefore:

○ breaking down the waterproof barrier that prevents excess moisture from entering the skin

○ reducing the natural lubrication that coats and protects the skin from drying out and becoming brittle, making it easier to break the skin open with pressure, trauma, and shear forces

○ allowing excess moisture to macerate the skin, increasing accessibility of the deeper layer to pressure and shear forces

Fewer Sweat Glands

○ Prevents perspiration with the exposure to excessive heat

○ Prevents the evaporation of sweat and the ability to cool the skin's temperature at the skin-seat interface

Change Happening at: Dermis

Layers of Skin Affected: ALL

How does decreased vacularization affect skin integrity?

Weaker blood vesselsand compromised blood flow make skin more susceptible to a pressure injury by increasing:

○ risk of ischemia and tissue death due to constant pressure under a bony prominence

○ risk of tearing of the blood vessels, causing permanent cell deformation and death caused by shear forces

Change Happening at: Dermis

Layers of Skin Affected: ALL

Why is it detrimental to our skin when collagen and elastin fibers become disorganized and reduced in number?

Loss of collagen and elastin fibers:

○ decrease skin's tensile strength and elasticity, making the skin unable to "snap back" to its original position after a load has been removed

○ risk of tearing of the blood vessels, causing permanent cell deformation and death caused by shear forces

Change Happening at: Dermis

Layers of Skin Affected: ALL

Why does a loss in Langerhans cells increase out susceptibility to pressure and shear?

Langerhans cells act as the body's warning against infection or high-pressure. The epidermal layer will redden and/or get warm as a warning sign to patient or caregiver to make a change!

Loss of Langerhans cells from disease or age:

○ slows the natural immune response of skin reddening and/or temperature change that acts as the initial warning signs of injury to the skin with pressure and/or trauma

○ increases susceptibility to prolonged pressure without an obvious warning sign to take precaution

Change Happening at: Epidermis

Layers of Skin Affected: ALL

What role does the dermal-epidermal junction play in maintaining healthy skin?

The dermal-epidermal junction is the communication channel between the dermis and the epidermis, allowing nutrients, O2, and blood to feed the epidermis and maintain skin integrity.

The dermal-epidermal junction is joined by wavy, finger-like projections called Rete Ridges. Rete Ridges increase the surface area to allow the flow of much needed nutrients, O2, and blood between the epidermis and dermis to maintain healthy skin.

How does the flattening of the dermal-epidermal junction affect skin integrity?

With age, thedermal-epidermal junction flattens by 35%, decreasing blood flow, O2, and nutrient exchange between the dermis and epidermis,

○ Results in the thinning of both layers of the skin

○ Prevents the natural keratinization needed for maintenance and healing of the skin after injury

Thinner epidermal and dermal layers:

○ causes a reduction in the barrier between the bony landmark and the pressure source

○ increases the susceptibility of the epidermis to break open at the bony prominences with pressure or trauma with shear forces

Change Happening at: Epidermis, Dermis

Layers of Skin Affected: ALL

Is sensation affected by disease and age?

Age causesnerve endings to lose their effectivenessto perceive and react to stimuli, decreasing the ability to perceive input from pressure, heat, and cold.

Did you know that loss in effectiveness of nerve endings decreases the ability to perceive pain from pressure build-up under bony prominences? This results in decreased reaction time in performing pressure relieving techniques, which can result in a pressure injury.

Change Happening at: Dermis, Hypodermis

Layers of Skin Affected: ALL

What happens to the hypodermis with age and disease that places the deeper tissues, muscles, and bone at risk of pressure injury?

There is areduction in the thickness of the hypodermis (fatty layer) due to:

○ the redistribution of fat cells

○ the loss of connective tissue

We never lose the number of fat cells we have. With age, fat cells are redistributed to areas of greater surface areas such as the stomach and thighs, leaving the areas under bony prominences more susceptible to the extrinsic factors of a pressure injury. Redistribution of fat cells to areas of great surface areas such as the stomach and thighs reduces the insulation and protective "cushion" the hypodermis normally would provide. A loss in connective tissue causes skin to be less firm. The skin then:

○ loses its strength and shape, becoming more susceptible to prolonged pressure at the bony prominences

○ loses fibrous bands that connect the skin to deeper tissues, making the deep tissue more susceptible to shear forces with movement in the wheelchair system

○ has diminished thermoregulation and absorbs more heat than it dissipates, making tissue more susceptible to the effects of pressure, shear, and microclimate

Change Happening at: Hypodermis

Layers of Skin Affected: ALL

Extrinsic Factors

Intrinsic vs Extrinsic Factors

Patients are susceptible to pressure injuries in a seated posture due to the effects of intrinsic and extrinsic factors of a pressure injury.

What are Intrinsic Factors?

Factors stemming from within the body that make an individual more susceptible to a pressure injury, such as:

○ Limited mobility

○ Impaired sensation

○ Age-related skin changes

○ Postural deformities

○ Poor nutrition and dehydration

○ Urinary and fecal incontinence

○ Obesity

○ Being underweight

○ Limited alertness

○ Muscle spasms

○ Smoking

○ Medical conditions affecting blood flow

What are Extrinsic Factors?

Factors that stem from the outside environment and/or seating surface. Pressure, shear, and microclimate are the extrinsic factors of a pressure injury.

The therapist can prevent harmful effects of extrinsic factors through proper wheelchair positioning and equipment choices.

The Three Extrinsic Factors

Let's take a look at the extrinsic factors and threat they pose to our patients while seated!

Pressure

Pressure is a continuous force applied on or against an object by something that it is in contact with. In seating, equipment such as the seat and/or back support surface are in constant contact with the body creating peak pressures.

Shear

Shear is defined as a combination of downward pressure AND friction and occurs while a patient is in movement in the wheelchair system.

How is the mechanism of pressure different from the mechanism of shear?

The Mechanics of Pressure

Peak pressures develop at the bony prominences caused by the downward pressure from gravity plus the upward pressure from the seated surface.

The skin/soft tissue between the bony prominences and the seat surface is constantly being compressed.

The lack of blood flow, O2, and nutrient delivery results inischemia.

Result in tissue death.

The Mechanics of Shear

Gravity causes downward pressure from prolonged sitting.

The patient moves/slides in the chair, causing friction.

The skin/tissue at the seat surface DOES NOT move while the underlying bone structure DOES.

The skin/tissue is strained by the combined pressure and friction.

Permanent cell deformation and distortion occurs at the deeper layers of tissue.

Blood vessel damage decreases oxygen delivery.

Ischemia.

Result is tissue death.

Microclimate

Microclimate is the climate of a very small or restricted area that differs from the climate of the surrounding area. It usually occurs under the bony prominence where pressure is at its peak, creating excessive heat and/or moisture build-up at the seat and/or back support surface.

What skin changes make a patient more susceptible to microclimate?

○ prevent the evaporation of sweat and the ability to cool the skin's temperature at the skin-seat interface

A decreased number sebaceous glands.

Less sebum (oil) production removes the oily coating from the superficial layer of skin:

○ breaking down the waterproof barrier that prevents excess moisture from entering the skin

○ reducing the natural lubrication that coats and protects the skin from drying out and becoming brittle, making it easier to break the skin open with pressure, trauma, and shear forces

○ allowing excess moisture to macerate the skin, increasing accessibility of the deeper layer to pressure and shear forces

How does microclimate increase the effects of pressure and shear?

Raised skin temperature and excessive moisture weaken the outermost layer of skin, making the deeper layers, tissue, muscle, and bone more susceptible to pressure and shear forces.

Elevated body temperature:

○ increases metabolic rate, in turn increasing the demand of O2to be delivered to the tissues

○ however, pressure and shear cut off O2supply

○ so, as demand increases but supply decreases, ischemia occurs more quickly than when the body temperature is normal

Elevated moisture:

○ increases the skin's coefficient of friction, making the skin and deeper tissues "stick" more easily to the seat surface when shear forces are applied

○ weakens the collagen fiber connections between the dermis and the epidermis and increases the risk of maceration

○ increases risk of maceration of the superficial layers of skin, which exposes the blood vessels in the deeper layers. This makes the blood vessels more susceptible to tearing and damage from shear and pressure

PressureRedistribution

Preventing the Band-Aid Effect: A Simple Equation

When a referral comes in due to falls from a wheelchair system, the development of a pressure injury or even a patient sliding into abnormal postures more frequently, our minds immediately jump to the seat surface as the culprit. “What cushion are they currently on? Is it the wrong style or is it worn out and need to be replaced?” However, when considering the optimal seating system we need to understand that cushions alone cannot solve all seating issues! We need to consider the interplay between the seat surface- the cushion, the back support and the wheelchair model and configuration in order to reduce the risk of:

○ A pressure injury

○ Falls from the seated posture

○ Decrease in function

○ Serious health complications that may arise due to poor posture in the wheelchair system

When we replace the cushion alone, we are simply putting a band aid on, masking the real issue that will eventually “fall off” leading to repeat referrals until we fix the root cause!

Pressure Redistribution

When we think of trying to heal an existing pressure injury or reduce the risk of the development of a new pressure injury, one rule of thumb should come to mind:

“The greater the surface area making contact with the seat and back support surfaces, the less risk of peak pressures”.

Offloading & Immersion

Offloading

The principle of offloading is one method of pressure redistribution. Partial or complete offloading can be achieved depending on the cushion’s construction. Partial offloading is most commonly seen. The cushion manufacturer uses contours in the cushion to produce “shelves and leg troughs” where the greater trochanter will sit and to delineate where the lower extremities will be for better alignment and contact with the seat surface. These contours redistribute pressure from the small surface area right under the sacrum to the larger gluteal surface and down the femur. As a result of the greater trochanters sitting “higher on the shelves”, the high risk areas of the sacrum, coccyx and ischial tuberosities are partially suspended and are prevented from making full contact in the pelvic well of the cushion. This is known as partial offloading and can be an effective way to add stability and relieve the high risk areas from constant pressure under the bony prominences.

Immersion/Envelopment

Immersion is another method of pressure redistribution. By allowing the body to immerse or “sink into” the medium of the cushion or back support, more contact is made over a larger part of the body. If you want to take it one step further, look for a cushion and back support that not only will “sink the body in” but will also wrap around it fully, capturing its “normal or abnormal” shape, known as envelopment. When the cushion or back support allows for both immersion and envelopment, even pressure of the gluteal surface and along the spine will be created, reducing the risk of pressure injury development.

Summary & References

How can I minimize the risk of a pressure injury in my practice setting?

• Understand the critical role addressing the seated posture plays in the wholistic approach to the prevention and treatment of a pressure injury.

• Educate yourself in the skin changes that make a wheelchair user more susceptible to a pressure injury.

• Understand the extrinsic factors of a pressure injury in relation to the seated posture.

• Acknowledge all the components in the simple equation that will result in an optimal seating system.

• Learn the methods of pressure redistribution, the benefits and considerations of each method, and the importance they play in the construction of a cushion and back support to prevent and treat a pressure injury.

When we as healthcare providers understand these key principles and attack pressure injuries from all support surfaces, then and only then do we have a chance to win the battle against pressure injuries!

Meet the Author

Ana Endsjo, MOTR/L, CLT

About Ana

Ana Endsjo has worked as an occupational therapist since 2001 in a variety of treatment settings. She has mainly worked with the geriatric population, dedicated to the betterment of the treatment of the elderly in LTC centers. Her focus has been on seating and positioning and contracture management of the nursing home resident. With this experience, her hope is to guide other therapists, rehab directors, nurses, and administrators through educational guides, blogs, webinars, and live courses in her role as Permobil's Clinical Education Manager of the Long Term Care Division.

27. Gefen, A. “How Much Time Does It Take to Get a Pressure Ulcer? Integrated Evidence from Human, Animal, and in Vitro Studies.” Ostomy/wound Management. U.S. National Library of Medicine, Oct. 2008. Web. 20 July 2017.